U.S. patent application number 16/510229 was filed with the patent office on 2020-01-16 for recycling of smart windows.
This patent application is currently assigned to Polyceed Inc.. The applicant listed for this patent is Polyceed Inc.. Invention is credited to Anoop AGRAWAL.
Application Number | 20200016641 16/510229 |
Document ID | / |
Family ID | 67659942 |
Filed Date | 2020-01-16 |
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United States Patent
Application |
20200016641 |
Kind Code |
A1 |
AGRAWAL; Anoop |
January 16, 2020 |
RECYCLING OF SMART WINDOWS
Abstract
The present invention relates to the methods of recycling
electrochromic devices and also designing such devices while
keeping recyclability in perspective. Recyclability includes
recovering of certain materials for re-use within the same
application or other applications. Using recycling reduces or
eliminates waste stream quantities to be disposed of and/or reduces
toxicity of these waste streams.
Inventors: |
AGRAWAL; Anoop; (Tucson,
AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Polyceed Inc. |
Tucson |
AZ |
US |
|
|
Assignee: |
Polyceed Inc.
Tucson
AZ
|
Family ID: |
67659942 |
Appl. No.: |
16/510229 |
Filed: |
July 12, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62698119 |
Jul 14, 2018 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22B 23/00 20130101;
B29B 17/0404 20130101; B09B 3/0083 20130101; B29B 2017/0244
20130101; B29B 2017/0268 20130101; B09B 3/00 20130101; C03C 1/002
20130101; B29B 17/02 20130101; C22B 7/007 20130101; C22B 11/046
20130101; B29B 2017/0203 20130101; C22B 25/06 20130101; C08J 11/06
20130101; B29B 2017/0468 20130101; C03C 1/024 20130101; C22B 34/36
20130101; B09B 5/00 20130101; B29B 2017/0496 20130101; C22B 58/00
20130101; B09B 3/0016 20130101; B29L 2031/778 20130101; C01D 15/00
20130101; C22B 26/12 20130101 |
International
Class: |
B09B 3/00 20060101
B09B003/00; C03C 1/00 20060101 C03C001/00; C03C 1/02 20060101
C03C001/02; C08J 11/06 20060101 C08J011/06; C01D 15/00 20060101
C01D015/00; C22B 7/00 20060101 C22B007/00 |
Claims
1. A method of recycling an electrochromic glass window comprising
glass and organic components, the method comprising: breaking the
electrochromic glass window into pieces having an average size of
less than 100 cm.sup.2; and heating the said pieces to a
temperature lower than the glass transition temperature of the said
glass to incinerate the organic components without melting the
glass.
2. The method of claim 1, wherein the electrochromic glass window
comprises one or more metals or metal compounds, the method further
comprising treating the said pieces in an acidic solution having a
pH of less than 3 to dissolve at least one of lithium silver,
indium, rhodium, ruthenium, tungsten, nickel, and tin from the
pieces into the acid solution.
3. The method of claim 1, wherein the electrochromic glass window
comprises one or more organic components and one or more metal
compounds, the method further comprising treating the said pieces
with a liquid composition comprising an organic solvent to extract
at least one of the organic components and metal compounds.
4. The method of claim 1, where the incineration is carried out in
oxygen or reducing conditions.
5. The method of claim 1, wherein after the incineration, a mixture
of glass, metal nuggets, and ash are obtained, the method further
comprising separating the glass, metal nuggets, and ash after the
incineration step.
6. A method of recycling an electrochromic glass window comprising
glass and one or more metals and metal compounds, the method
comprising: breaking the electrochromic glass window into pieces
having an average size of less than 100 cm.sup.2; and treating the
said pieces in an acidic solution having a pH of less than 3 to
dissolve at least one of lithium, rhodium, ruthenium, silver,
indium, tungsten, nickel, and tin from the pieces into the acid
solution.
7. The method of claim 6, wherein the electrochromic glass window
comprises one or more organic components, and wherein the method
further comprises heating the said pieces to a temperature less
than the glass transition temperature of the said glass to
incinerate the organic components without melting the glass.
8. The method of claim 6, wherein the electrochromic glass window
comprises one or more organic components and one or more metal
compounds, the method further comprising treating the said pieces
with a liquid composition comprising an organic solvent to extract
at least one of the organic components and metal compounds.
9. The method of claim 6, wherein the method further comprises
heating the acidic solution in a temperature range of about
40.degree. C. to about 100.degree. C.
10. The method of claim 6, further comprising extracting at least a
portion of the metals dissolved in the acid solution from the acid
solution in a metal recovery process.
11. The method of claim 10, further comprising neutralizing the
acid after the metal recovery process.
12. The method of claim 6, further comprising treating with water
to (a) remove water soluble components, (b) remove liquid
components, (c) de-adhere polymeric component and glass component,
or (d) a combination of any of (a), (b), and (c).
13. The method of claim 12, wherein the electrochromic glass window
further comprises more than one polymeric component, the method
further comprising separating two or more polymeric components from
each other based on their physicochemical properties.
14. The method of claim 6, wherein the electrochromic glass window
further comprises one or more plastics, wherein a floatation method
is used to separate at least one of the plastics, metals and
glass.
15. A method of recycling an electrochromic glass window comprising
glass, one or more organic components, and one or more metal
compounds, the method comprising breaking the electrochromic glass
window into pieces having an average size of less than 100
cm.sup.2; and treating the said pieces in a liquid composition
comprising an organic solvent to extract at least one of the
organic components and metal compounds.
16. The method of claim 15, further comprising heating the said
pieces to a temperature less than the glass transition temperature
of the said glass to incinerate the organic components without
melting the glass.
17. The method of claim 15, further comprising dissolving the said
pieces in an acidic solution having a pH less than 3 to dissolve at
least one of lithium, rhodium, ruthenium, silver, indium, tungsten,
nickel, and tin from the pieces into the acid solution.
18. The method of claim 15, wherein the electrochromic glass window
comprises an organic electrolyte layer comprising one or more
organic compounds and one or more metal compounds, the method
further comprising extracting at least one of the organic
components and the metal compounds from the organic electrolyte
layer.
19. The method of claim 15, further comprising extracting a lithium
salt from the electrochromic glass window.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority benefit of U.S.
provisional application Ser. No. 62/698,119, filed Jul. 14, 2018,
which is incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to methods for recycling of
smart windows and products used in buildings and
transportation.
BACKGROUND OF INVENTION
[0003] Smart windows are complex, multi-component electrochemical
structures that change color, opacity, and/or transparency with the
application of a voltage. Used in buildings and for transportation,
these smart windows provide shade, energy savings, privacy,
partitions and so forth. The user may control the heat and/or light
that passes through the glass using electronic switching, rather
than using mechanical shades. The element of these smart windows
which results in this optical change is usually based on an
electrochromic (EC) device or a liquid crystalline (LC) device.
Several examples in this disclosure refer to EC devices, but the
recyclability principles also apply to the LC devices. These
principles may also be used to recycle EC automotive mirrors.
[0004] Used in buildings and in transportation windows, these
products result in energy efficient building envelopes and
increased comfort by regulating the solar energy penetration
through the windows. As these window systems become ubiquitous it
is important that these are recycled at the end of their life so
that the impact on the resources and environment is minimized. In
addition, such systems should be designed using materials and
technologies so that it is easier for them to be recycled
(recycling includes any of the following, re-use of certain
materials, conversion of materials for other uses, recovering some
of the higher value materials, reducing the waste to be disposed
of) using minimum resources and causing minimum harm to the
environment when the effluents are discharged. The latter refers to
reducing toxicity of the waste streams prior to their
discharge.
[0005] FIG. 1 shows a general concept of a product manufacturing
and its recyclability including demanufacturing steps. The raw
materials are initially obtained from the environment which are
mined and then processed into intermediate materials or parts which
are then used to manufacture the product which is then distributed
and used. After its use-life is completed it is taken back by the
same party which had originally distributed the product or another
party. This party may find another use for the product or it is
submitted for demanufacturing. Demanufacturing means that the
product is disassembled and/or is broken down. Some or all of these
parts may be used again for the manufacturing of the new products,
or some materials are reclaimed or demanufactured which are then
cycled back into a similar new product or alternative uses are
found. Further some of the components may be converted to materials
or fuels, and in the conversion process energy is produced (e.g.,
by incineration of some components) which is recovered or used and
a smaller fraction of waste may be produced safe for disposal into
the environment. The objective here is to teach processes and
methods for demanufacturing of smart window products and taking
them through the end-of life cycle as explained above. In addition,
teachings are also incorporated on how to design the smart windows
in the first place so that they are easier and safer to
demanufacture, recycle and dispose of.
[0006] It is important to keep in mind that during demanufacturing,
it is not necessary that all materials must be restored to their
pristine form and reused in the same application or to make the
same product. In most instances it is sufficient that these be
separated into waste streams which could be gainfully employed (or
used) by other industries without creating huge waste dumps or
disposable wastes which are toxic. The other industries may recover
materials from these more efficiently or they may be able to use
these in manufacturing of other products.
[0007] The reuse and recycling concepts are increasingly becoming
popular and are being required for a variety of products as they
enter into the end of life phase, because their simple disposal is
not being permitted in many regions of the world. Some of these in
the energy area include batteries, solar cells, wind mills, etc.
The objective of this patent is to teach recycling and disposal of
smart windows used in buildings and transportation.
SUMMARY OF THE INVENTION
[0008] The present disclosure includes a method of recycling an
electrochromic glass window comprising glass and organic
components, the method comprising: breaking the electrochromic
glass window into pieces having an average size of less than 100
cm.sup.2; and heating the said pieces to a temperature lower than
the glass transition temperature of the said glass to incinerate
the organic components without melting the glass. In some aspects,
depending on the glass transition temperature of the glass, the
heating may be, for example, to a temperature between 250.degree.
C. to 500.degree. C., 275.degree. C. to 450.degree. C., 300.degree.
C. to 400.degree. C., or any temperature or combination of
temperatures in any of the recited ranges.
[0009] The present disclosure also includes a method of recycling
an electrochromic glass window comprising glass and one or more
metals and metal compounds, the method comprising: breaking the
electrochromic glass window into pieces having an average size of
less than 100 cm.sup.2; and treating the said pieces in an acidic
solution having a pH of less than 3 to dissolve at least one of
lithium, rhodium, ruthenium, silver, indium, tungsten, nickel, and
tin from the pieces into the acid solution.
[0010] The present disclosure also includes a method of recycling
an electrochromic glass window comprising glass, one or more
organic components, and one or more metal compounds, the method
comprising breaking the electrochromic glass window into pieces
having an average size of less than 100 cm.sup.2; and treating the
said pieces in a liquid composition comprising an organic solvent
to extract at least one of the organic components and metal
compounds.
[0011] The present disclosure also includes recycled products
formed by the methods of the present disclosure. The present
disclosure also includes newly manufactured glass and
electrochemical devices made using the recycled products formed by
the method of the present disclosure.
[0012] Other features and characteristics of the subject matter of
this disclosure, as well as the methods of operation, functions of
related elements of structure and the combination of parts, and
economies of manufacture, will become more apparent upon
consideration of the following description and the appended claims,
all of which form a part of this specification.
BRIEF DESCRIPTION OF FIGURES
[0013] FIG. 1 illustrates a schematic representation of a product
lifecycle including its manufacturing, demanufacturing, recycling
and disposal;
[0014] FIG. 2 illustrates schematics of a few different
configurations of a dual pane Integrated Glass Unit (IGU)
comprising a smart window;
[0015] FIG. 3 shows a schematic route for materials recovery and
recycling of an EC product at the end of its life;
[0016] FIG. 4 shows a schematic route for materials recovery and
recycling of an EC product at the end of its life;
[0017] FIG. 5 shows a schematic route for materials recovery and
recycling of an EC product at the end of its life;
[0018] FIG. 6 illustrates exemplary electrochromic (EC) device
structures.
DETAILED DESCRIPTION
[0019] While aspects of the subject matter of the present
disclosure may be embodied in a variety of forms, the following
description is merely intended to disclose some of these forms as
specific examples of the subject matter encompassed by the present
disclosure. Accordingly, the subject matter of this disclosure is
not intended to be limited to the forms or embodiments so
described.
[0020] The singular forms "a," "an," and "the" include plural
referents unless the context clearly dictates otherwise.
[0021] Concentrations, amounts, and other numerical data may be
expressed or presented herein in a range format. It is to be
understood that such a range format is used merely for convenience
and brevity and thus should be interpreted flexibly to include not
only the numerical values explicitly recited as the limits of the
range, but also to include all the individual numerical values or
sub-ranges encompassed within that range as if each numerical value
and sub-range is explicitly recited. As an illustration, a
numerical range of "about 0.01 to 2.0" should be interpreted to
include not only the explicitly recited values of about 0.01 to
about 2.0, but also include individual values and sub-ranges within
the indicated range. Thus, included in this numerical range are
individual values such as 0.5, 0.7, and 1.5, and sub-ranges such as
from 0.5 to 1.7, 0.7 to 1.5, and from 1.0 to 1.5, etc. Furthermore,
such an interpretation should apply regardless of the breadth of
the range or the characteristics being described. Additionally, it
is noted that all percentages are in weight, unless specified
otherwise.
[0022] In understanding the scope of the present disclosure, the
terms "including" or "comprising" and their derivatives, as used
herein, are intended to be open ended terms that specify the
presence of the stated features, elements, components, groups,
integers, and/or steps, but do not exclude the presence of other
unstated features, elements, components, groups, integers and/or
steps. The foregoing also applies to words having similar meanings
such as the terms "including", "having" and their derivatives. The
term "consisting" and its derivatives, as used herein, are intended
to be closed terms that specify the presence of the stated
features, elements, components, groups, integers, and/or steps, but
exclude the presence of other unstated features, elements,
components, groups, integers and/or steps. The term "consisting
essentially of", as used herein, is intended to specify the
presence of the stated features, elements, components, groups,
integers, and/or steps as well as those that do not materially
affect the basic and novel characteristic(s) of features, elements,
components, groups, integers, and/or steps. It is understood that
reference to any one of these transition terms (i.e. "comprising,"
"consisting," or "consisting essentially") provides direct support
for replacement to any of the other transition term not
specifically used. For example, amending a term from "comprising"
to "consisting essentially of" would find direct support due to
this definition.
[0023] As used herein, the term "about" is used to provide
flexibility to a numerical range endpoint by providing that a given
value may be "a little above" or "a little below" the endpoint. The
degree of flexibility of this term can be dictated by the
particular variable and would be within the knowledge of those
skilled in the art to determine based on experience and the
associated description herein. For example, in one aspect, the
degree of flexibility can be within about .+-.10% of the numerical
value. In another aspect, the degree of flexibility can be within
about .+-.5% of the numerical value. In a further aspect, the
degree of flexibility can be within about .+-.2%, .+-.1%, or
.+-.0.05%, of the numerical value.
[0024] Generally herein, the term "or" includes "and/or."
[0025] As used herein, a plurality of compounds or steps may be
presented in a common list for convenience. However, these lists
should be construed as though each member of the list is
individually identified as a separate and unique member. Thus, no
individual member of such list should be construed as a de facto
equivalent of any other member of the same list solely based on
their presentation in a common group without indications to the
contrary.
[0026] Furthermore, certain compositions, injuries or conditions,
steps, or the like may be discussed in the context of one specific
embodiment or aspect. It is understood that this is merely for
convenience, and such disclosure is equally applicable to other
embodiments and aspects found herein.
[0027] FIG. 2 shows schematics of an integrated glass unit (IGU),
i.e., a smart window construction for use in a building which
contains an electrochromic (EC) element. This unit comprises of a
dual pane structure where the outer pane is an EC element which
uses glass substrates and the inner pane is a glass sheet. These
are separated by a gap which is typically filled with a gas. It may
be filled with dry air or nitrogen, but usually it is preferred
that a low conductivity gas be used such as argon, krypton, sulfur
hexafluoride, and mixture of these gases, which may be further
mixed with dry air and/or nitrogen. The glass panes are separated
at the perimeter by spacers which are bonded to these two panes,
generally using a butyl adhesive as that is flexible and has low
gas permeability. The spacers may be metallic or these could be
polymeric or composites such as glass reinforced polymers. The
surfaces of the panes facing the outside of the building, gap and
the building inside are numbered 1 through 4 starting from the
outside surface. Further, one of the surfaces 2, 3 or 4 is coated
with a low emissivity (low-e) coating. This coating is not shown in
this figure. An electrical connector is also shown that connects
the EC unit to a power supply or any other wired controllers and
sensors which may be used. The electrical connectors may comprise
additional leads connected to sensors for measuring temperature and
other properties used for fine tuning the powering protocol to get
the desired optical characteristics. Depending on the application
and the removal of the window from the site for disposal, the smart
window may refer to only the EC and/or the LC panel, may be a
complete IGU unit comprising the EC and/or the LC panel, or even a
complete IGU unit mounted in a window frame. The frames may be made
out of metal, wood and plastics such as poly vinyl chloride,
polyester (includes glass reinforced polyester), etc. IGU's also
include metal or flexible plastic spacers made out of extruded
profiles using polyurethanes, butyls and may also contain metallic
reinforcing cores, sealants such as butyls (including
polyisoprene), polysulfides, polyurethanes and silicones are also
used in addition to the spacers. For example, IGUs are routinely
used in the buildings and the EC panel may be further laminated.
The window construction may include other variations, such as
triple glass constructions, constructions with vacuum insulated
glass, etc. EC panels used for interior partitions in buildings and
may not be in an IGU configuration. EC panels with or without
lamination to other glass or plastic panels may be used in
transportation industry, like glazing for automotive, planes,
trains, boats, etc.
[0028] The above example of the IGU uses friable substrates,
generally glass both in the inner pane and in the construction of
the EC element. Friable substrates are those which can be broken
into pieces or crushed into a powder upon impact and include
various types of glass including, but not limited to chemically- or
heat-strengthened glass, e.g., tempered glass. One method of
recycling involves recovering friable material, recovering metallic
materials, particularly those which may be toxic or of higher
value, and recovering energy by pyrolysis of organic and polymeric
materials.
[0029] The process of recycling/materials recovery starts by
removing the IGU unit from the window frame and cutting its
electrical connection with the electronics. The electronics may be
left in place and reused or it may be also removed and recycled
using standard methods used in the electronics industry. In one
embodiment the two panels comprising the IGU are separated from the
perimeter spacers (which are channel type construction running
along the perimeter) by cutting through the adhesive (typically
butyl adhesive). This may be accomplished more easily by using a
heated knife (blade). The channels if metallic may be reused (or
the metal reclaimed) after cleaning or burning the residual
adhesive. If these channels are polymeric then these are cut or
shredded and processed with other polymeric waste as discussed
below.
[0030] FIG. 3 shows schematics of a process where the two separated
panels of the IGU are recycled and materials reclaimed when there
are no organic and polymeric materials in the separated panes.
These may be recycled independently or together following this
procedure. In Step 1, the panels, principally formed from friable
materials such as glass are crushed using impact such as a hammer
or a hammer mill to a desired size and passed through a sieve so
that the larger pieces can continue to be hammered until the size
is reduced to a size lower than the sieve size. This size may be
any, however in one embodiment the average size is smaller than 10
square cm, and in another embodiment this may be smaller than 50
square cm and yet in another embodiment this may be smaller than
100 square cm. Fine powder may also be created in this process,
thus the average size of glass is determined by weight averaging
various pieces and after removing any polymeric or glue pieces that
may cause several pieces to stick to each other.
[0031] The crushed panels are subjected to a dissolution solution
in step 2. The purpose of the dissolution solution is to dissolve
metals and metal compounds which may have been deposited as
coatings on the panels. In electrochromic devices some of the metal
and or metal oxide coatings containing principally indium, tin,
tungsten, nickel, lithium, chromium, cobalt, vanadium, molybdenum
and phosphorous. The low-e glass coatings will have silver, zinc,
aluminum, titanium and silicon containing layers. Of these the
higher value metals are indium, silver, lithium, silver, cobalt and
tungsten. These dissolution solutions may be highly basic or highly
acidic. Highly acidic aqueous solutions such as those comprising
sulfuric acid, nitric acid, hydrochloric acid and their mixtures
are preferred as these do not attack glass as aggressively and
still are able to solvate a wide variety of metals and metal
oxides. The acid solutions in this invention are characterized in
one embodiment as a pH of 3 or lower, and in another embodiment as
a pH of 2 or lower and yet in another embodiment as a pH of 1 or
lower. These may also be aided by oxidizing agents (e.g., hydrogen
peroxide) or reducing agents, etchants (e.g., ferric chloride)
depending on the chemistry and physicochemical properties of the
materials to be removed and surfactants suitable for use in acidic
or the basic medium (e.g., Niaproof 4 and Niaproof 8 from Niacet
Corp (Niagra Falls, N.Y.)). As an example, these solutions may be
made in water where the acid may be present by weight in 5 to 30%,
oxidizing or reducing agents 0.1 to 30 weight percent, surfactants
0.001 to 2%. This dissolution may be conducted at room temperature
or at an elevated temperature (usually in a range of about
40.degree. C. to 100.degree. C.) to enhance solvation rate. The
dissolution may be conducted in acid resistant (or base resistant
as the case may be) barrels by tumbling, rotating and/or stirring
the mixtures.
[0032] After the dissolution step, the solids mainly glass is
separated (step 3) from the liquids. The recovered glass solids
(Step 4) may be rinsed further with water and/or dissolution
solvent, which may also be added to the separated liquid. The glass
solids may be pulverized and re-used to make glass plates by
melting or may be used for a different purpose.
[0033] In Step 5, the liquids are recovered which have dissolved
metals.
[0034] In step 6, the liquids are used to recover the metals (or
metal compounds), by using a variety of processes. This can be done
by a series of precipitation processes and/or also by
electrochemical deposition and ion exchange. The recovered metals
in step 7 may be reused or sold (or this liquid may be sold to a
processor for metals recovery). The remaining liquid (step 8) after
the metals recovery (if acidic) may be neutralized with a base
(such as sodium hydroxide) and disposed of as harmless salts or the
acids are recovered to be used again.
[0035] It should be noted that some or all of the steps from Step 2
to Step 6 may be conducted in several series of steps, where one
may treat the materials with a first acid treatment which removes
specific metals, which are then recovered from the liquid, the
solids are then subject to the next acid treatment (where the
composition of acid solution is different) and then the next set of
metal(s) is recovered and so on. Or in another variation several
metals are dissolved in the solution, but the separation of
specific metals is a series of steps such as a step by step process
where these may be precipitated or recovered sequentially, e.g., by
changing the pH and also adding materials that cause specific metal
compounds to be formed at those pHs. This removal of metals as
compounds may be reduced to pure materials in Step 8 if desired by
electrochemical processes or heating the separated metal compounds
under reducing conditions.
[0036] In Step 8 one may recover specific ingredients from the
liquid for reuse or neutralize the acids (or bases) for safe
discharge.
[0037] In one embodiment the glass compositions used for all
components are similar, including their color. This means that the
glass can be recycled and converted to glass sheets for use in the
same application or any other application without any change in its
optical, mechanical or thermal properties. For glazing
applications, it is preferred that soda-lime glass compositions are
used for all of the panels. This is an important consideration when
the products are being designed to include recyclability as a
criterion. When glasses with dissimilar compositions (or inherently
different colors) are mixed they may be difficult to recycle to
reuse them in a single glass composition due to limited
applications of glass with uncontrolled color. For example, the
processing profile (e.g., glass transition temperature and flow
point) of soda lime glass is very different from that of
borosilicate glass. Similarly, when glass compositions of different
colors are mixed then it is difficult to control color of these
mixtures for remanufactured pristine objects or they may be used
for applications where color control from batch to batch is not
important. Additionally, it is desirable to mark the glass with a
sign separating them in different classes so that during recycling
similar classes may be easily identified and mixed. In many cases
the EC glass substrate may have certain color to provide a specific
appearance (e.g., a color) from the outside of the building. In
such cases it is desirable from a recycling perspective that such
colors be added as coatings of metals and metal compounds rather
than adding them to the glass compositions. When the latter is
done, then these coatings are removed by the dissolution solution
(steps 2-4) and does not end up as a contaminant in the recovered
glass.
[0038] FIG. 4 shows a recycling process for an EC window which
constitutes organic layers also comprising polymeric materials.
These layers may be part of an EC device (discussed later in FIG.
6) and/or may be external to the EC devices. When polymeric
materials are used to laminate an already formed EC device to
another sheet of glass or a polymeric sheet, then this arrangement
is considered external to the EC device. For building windows it is
more common to laminate EC panels to another glass sheet, whereas
in automotive application the probability of using a plastic sheet
to bond to a glass component is higher. For those windows which use
EC panels like the ones described earlier when discussing FIG. 3,
i.e., no organic layers are used within the EC structure, and the
organic component is mainly from the lamination materials, the
recycling method may be used as described in FIG. 4.
[0039] FIG. 4 shows a recycling method where the windows are
crushed as depicted in step 1a (similar to step 1 of the process
shown in FIG. 3). However due to the lamination aspect large pieces
of polymeric material may remain attached to small broken pieces of
glass. Thus, the crushed product is separated by size (as in Step 1
of FIG. 3) and collected, and the larger pieces of polymer to which
smaller pieces of glass are still adhered to is taken to Step 1b
and the pieces are shred (primarily the polymer is shred) and taken
to Step 1c. Although because of mechanical processing Steps 1a and
1b, the adhesion between the glass and the polymer is substantially
weakened. In this step polymer pieces adhered to glass are subject
to large tumbling forces in presence of water. This further weakens
the adhesion and the glass and polymer separate, in addition any
water-soluble components (e.g., plasticizers in the polymer, salts
or other components) are removed from these pieces. Water may be
heated in this process generally in the range of about 40 to
100.degree. C., to assist with increasing the process yield i.e.,
more complete recovery and/or shortening of the processing time.
The solids are recovered and further processed in Step 1d. The
liquids are removed as in Step 5 and processed further. It is also
possible that liquid plasticizers in the electrolyte which are
insoluble in water are also removed, e.g., hydrophobic ionic
liquids if present. These can be largely separated by decanting due
to density differences between the water and this medium. These may
also be separated by using hydrophobic or hydrophilic filtration
mediums which only allow one of these types of materials to pass
through. Water soluble materials may also be recovered by drying
the water or adding other additives to precipitate the desired
materials. The use of water as a solvent in the specification is
different from aqueous acid solutions used for metal dissolution
discussed above, as the pH of water used usually ranges from about
4.5 to 9.5.
[0040] In FIG. 4 (Step 1d), the solid chunks are separated based on
their composition (such as pieces of polymers, metals and glass).
This may be done by various methods, such as separation by density
and surface chemistry (e.g. by floatation). One may even
distinguish further, where polymers may be separated into different
polymers, metals into different metals and so on. The metals pieces
may come into play primarily from the electrochromic devices where
metal tapes and connectors may have been used as busbars and
current carrying elements and pieces of metals are mingled into
this stream. The metal pieces (recovered in step 1d) may be cleaned
by processing at temperatures in excess of 250.degree. C. to
incinerate any polymeric (adhesive) residues, and in another
embodiment this temperature is 400 C or higher. The glass collected
in this step is combined with the glass pieces collected from step
1a and then as in Step 7 it is send for further processing to
recover metals from the coatings using dissolution (as was
discussed in steps 2 to 8 of FIG. 3, where the metal containing
coatings on glass are removed in an acidic solution and the pure
glass solids and metals from these coatings are recovered).
[0041] The busbars on the EC glass may also be formed by depositing
conductive lines around the perimeter using glass (or ceramic)
frits containing silver. These compositions typically comprise of
ceramics not found in usual glass compositions, and from a
recycling perspective it is difficult to remove them from the glass
compositions of the substrate. Thus, from a recycling perspective,
the use of metallic tapes is preferred. The tapes with z-axis
conductive adhesives (such as those available from 3M (St. Paul,
Minn.) may be used for the busbar as these are easy to separate and
recycle. Some examples of such tape products from 3M have product
ID numbers as 3007 and 3011.
[0042] Step 8 of FIG. 4 shows that the polymers are recovered,
which may be further separated based on floatation or other methods
(including differential melting points of the various polymers),
dried and recycled for various applications. Floatation properties
of polymers are also influenced by the additives present in them,
such as fillers and the wetting agents. Thus as long as the wetting
agents do not adversely interact with the desired properties that a
particular polymer imparts, for improving recyclability different
wetting agents to different polymeric layers are added so that when
these materials are recycled it is easier to separate various
polymers. Typically, when separating polymers by floatation a
preferred average particle size surface area range is from about 10
square mm to about 200 square cm, thus in one embodiment it is
preferred that the polymeric waste be reduced to this size. For,
example, the polymers may still contain additives such as water
insoluble plasticizers, UV absorbers, antioxidants, fillers, flame
retardants, antiblocking agents and processing aids, colorants,
polymer modifiers, wetting agents, etc. Such materials may be used
for a variety of applications and may be combined with other
materials such as recycled foams to form binders, carpet backings
or mixed with asphalt or used instead of asphalt for road
construction, etc. Some of the common materials used for laminating
glass sheets are poly vinyl butyral (PVB), thermoplastic
polyurethane (TPU), ethyl vinyl acetate (VA), fluorinated polymers,
etc. Again markings on windows identifying the type of lamination
resin would be helpful from a recyclability perspective so that the
waste streams are easy to identify. In some cases, plastic films or
EC elements made using flexible plastics as substrates are
laminated or bonded to glass substrates using another polymeric
laminating sheet or an adhesive. Such constructions may be used in
the automotive industry or for retrofitting these polymeric EC
elements on glass windows for buildings. In these cases, there is
an additional polymeric substrate material which in recycling has
to be separated from the laminated glass material. Typical plastic
sheet or film materials used for as substrates for making EC or LC
devices are clear stable polymers such as polyesters (typically
polyethylene terephthalate (PET), polyethylene naphthalate (PEN)),
polycarbonate, acrylics, fluorinated and chlorinated polymers and
copolymers such as those containing polyvinylidene fluoride (PVDF),
polyvinylidene chloride (PVDC) and
polyethylene-chloro-trifluoro-ethylene (ECTFE). Generally, acrylics
and polycarbonates are used in thicker sheet stock (high thickness
with rigidity, i.e., equal to or greater than about 1 mm in
thickness to about 10 mm), and the other materials are used as
films (usually 0.5 mm or less in thickness to down to about 0.025
mm). Again, markings on such window systems to alert the recycler
of the material composition are helpful to disassemble and tailor
the recycling process.
[0043] It is possible windows with different glass compositions may
end up in one waste stream, and they can be in applications which
have lower product value as discussed earlier. Further, if a
product is being designed for recyclability, and an enzymatic
and/or incineration process is involved in getting rid of organic
materials (and/or generating useful materials), it is preferred
that materials which cause heavy load of sulfur, fluorine and
chlorine are not used or used in smaller amounts so that the load
on scrubber containing acidic or fumes containing these materials
is reduced. This would mean using less of the fluorinated and the
chlorinated materials such as fluorinated and chlorinated polymers
and copolymers. In another embodiment these materials are not used
to improve recyclability.
[0044] Another solvent recovery step may be either substituted for
step 1c in FIG. 4 or inserted between the steps 1b and 1c (this
step is not shown in this figure). If there are specific
ingredients that need to be recovered prior to the water treatment,
organic solvent treatments may be used to accomplish this. In one
embodiment, the organic solvents are so selected are so that they
target reclaiming specific materials without solvating all of the
ingredients, e.g., this may be a non-solvent for some of the
polymeric species so that the increase in viscosity of the solution
during the recovery is low and high recovery efficacy of the target
ingredients is maintained. Introduction of this step or a series of
steps with different solvents to recover specific materials is
advantageous. This ensures that high purity of extracted materials
is maintained in each stream which reduces the burden of separating
them later. As an example, by introducing this step one may obtain
only the lithium salts and/or specific plasticizers if they are of
high value, such as ionic liquids and liquid crystal materials if
used.
[0045] Some examples of ionic liquids are salts of quartenary
ammonium cations of pyridinium, pyrrolidinium, pyridazinium,
pyrimidinium, pyrazinium, imidazolium, pyrazolium, thiazolium,
oxazolium, and triazolium. These may have various substitutions or
substituents, such as H, F, phenyl and alkyl groups with 1 to 15
carbon atoms. Rings may even be bridged. Saturated rings such as
pyrrolidinium are preferred for superior UV stability for clear
systems and they also tend to have superior electrochemical
stability range. The anions of these salts are typically fluorine
containing such as triflate (CF.sub.3SO.sub.3.sup.-), imide
(N(CF.sub.3SO.sub.2).sub.2.sup.-), beti
((C.sub.2F.sub.5SO.sub.2).sub.2N.sup.-), methide
(CF.sub.3SO.sub.2).sub.3C.sup.-), tetraflouroborate
(BF.sub.4.sup.-), hexaflourophosphate (PF.sub.6.sup.-),
hexafluoroantimonate (SbF.sub.6.sup.-), bis(fluorosulfonyl)imide
(N(FSO.sub.2).sub.2.sup.-) and hexafluoroarsenate
(AsF.sub.6.sup.-). Of these, imide, beti bis(fluorosulfonyl)imide
and methide anions are able to provide hydrobhobicity. An example
of a hydrophobic ionic liquid is 1-butyl-3-methyl pyrrolidinium
bis(trifluoromethanesulfonyl)imide (BMP). When in an electrolyte
ionic liquids and lithium salts are used, in some embodiments the
anion for both are similar.
[0046] Another EC window recycling scheme is shown in FIG. 5. In
this scheme, the organics are burnt off to produce energy and only
the metals and the glass are recovered. This scheme is particularly
useful when too many different organics and polymers are used where
it is not economically feasible to recover and separate them. In
Step 1 the windows are crushed. If the windows or the EC element
have a laminated layer which causes large pieces to form with
broken glass adhered to that then it is shred as in Step 1b, or
Step 1b may be skipped and go to step 1c. In Step 1c all the
materials are heated to temperatures less than the glass transition
temperature of soda--lime glass, i.e., the most used glass (in
another embodiment to temperatures at or less than about
400.degree. C.) to burn of all of the organic materials and the
energy is recovered and the gases are scrubbed. The minimum
temperature of burn organic materials in another embodiment is
300.degree. C. Some of the gases such as carbon dioxide may be
reused to make fuels or polymers. In step 1d, remnants of metals,
chunks of glass and ash is produced. In one embodiment, the
incineration is done in the presence of oxygen so as to obtain the
residue of metals as metal oxides. In another embodiment when
incineration is carried out under reducing conditions then metal or
metal oxides are formed interlaced with carbon containing soot.
Another way to treat the organic materials is by treating them with
enzymes so as to break these into more useful materials rather than
introducing carbon dioxide into the atmosphere. Some useful
materials are hydrogen, carboxylic acids, etc. The left over
organics after enzymatic digestion may be incinerated.
[0047] In FIG. 5, Step 1c, since the heating is carried out at
temperatures less than the glass transition (Tg) temperature of
glass, the glass pieces do not fuse and are easy to separate.
Metals are from connectors and conducting tapes. The metallic
chunks and glass chunks are separated from the fine powder, where
the fine powder (mainly metal oxides) may be used to recover high
value and toxic metals as discussed earlier by dissolving them in
an acidic solution. The glass and the metals may be pulverized
further under impact where the glass chunks will break further in
small pieces and the metals being malleable may end up as larger
flakes. These can be then separated based on size or flotation.
Some type of metals may also be removed or recovered using magnets.
Glass and metal may be recycled. If glass has residue of metallic
coatings this may be first treated with an acidic solution to
remove these before recycling (or reusing). The ash is treated with
acids to recover high value or toxic metals and any residue is
discarded. To recover metals from the glass (step 7) and ash (step
9), these two streams are combined (after metallic chunks have been
removed) and subject them to a common acid treatment.
[0048] FIG. 6 show two types of EC device constructions most often
used for windows. Additional layers may be used to promote
interfacial compatibility, reduce iridescence, enhance memory,
electrical conductivity, color, etc. In the Type A device an
Organic Electrolyte 3 is used. The device is made by taking a pair
of substrates, where the first substrate 1a is coated with a
transparent conductive (TC) layer 1b such as indium tin oxide or
other materials or be a combination of various layers. Similarly a
substrate 2a is also coated with a TC layer 2b. The layer 2a is
coated with an electrochromic (EC) layer such as containing
tungsten oxide, molybdenum oxide, vanadium oxide, nickel oxide and
lithium oxide. Layer 2b is coated with a counter electrode (CE)
layer 2c. Layer 2c may also be electrochromic and usually it is
complimentary to the EC layer, which means if the EC layer colors
upon reduction then the CE layer colors upon oxidation, so that
both layers either color when the coloring power is applied and
also both bleach when power to bleach is applied. A liquid crystal
device is similar to that shown in FIG. 6, but does not have an EC
and CE coatings and the electrolyte layer is substituted with a
polymeric layer containing a liquid crystalline material.
[0049] The counterelectrode 2c may comprise of a metal compound
(usually a metal oxide) selected from nickel oxide, cerium oxide,
titanium oxide, vanadium oxide, cobalt oxide and lithium oxide or
their combinations amongst themselves or with other materials. The
EC and/or the CE layers may also contain additional lithium which
reduces the oxidation state o metal in the metal compound. In a
variation of this device both or one of the EC layer and the CE
layer may also be formed by using a coating of an organic material
or mixtures of organic and inorganic materials. Organic electrolyte
3 in the above device comprises typically of polymers,
plasticizers, UV stabilizers and lithium salts. Some of the
plasticizers may be ionic liquids which are high value items and
their recovery is economically and environmentally beneficial, and
the lithium amount in this layer is present in a much higher amount
as compared to any of the other layers which may also be recovered.
Some of the polymers used in electrolytes comprise polyurethanes,
acrylics (includes PVB) and fluoropolymers. For recyclability as
discussed earlier in one embodiment fluoropolymers are less
preferred as in incineration higher amounts of halogens are given
off. Some of the non-ionic plasticizers include propylene
carbonate, diethylene carbonate, gamma-butyro lactone, tetraglyme,
sulfolane, ionic liquids, esters and their mixtures. Since
sulfolane causes a sulfur load for recycling, in one embodiment,
sulfolane is not used or is a less preferred option. A few of the
common lithium salts are lithium perchlorate, lithium
tetrafluoroborate, lithium hexaflurophosphate and lithium
bis-trifluoromethanesulfonimide. All of these lithium salts are
water soluble. All of the lithium salts contain halogens, but since
their use in an EC device is small relative to the other components
these are not expected to cause a large overload of gases in case
incineration process is used to get rid of the organic
components.
[0050] In EC windows and commercial EC devices, the weight of the
electrolyte is typically less than 5%, and more often less than 1%.
In one embodiment, for devices with high potential to recycle, the
amount of lithium salt in these devices is less than 20% by weight
and more than 1% by weight, based only on the electrolyte weight.
In another embodiment for recyclable devices the weight of the
lithium salt is less than 10% by weight of the electrolyte, and yet
in another embodiment it would be less than 5% of the weight of the
electrolyte.
[0051] There are other types of devices which use two substrate
constructions and are commonly used for automotive mirrors and
aircraft windows. In these there is no CE or EC layer, but the
electrolyte contains redox dyes in addition to the components
mentioned above. Yet in another variation the EC layer is there but
the CE is replaced by a redox dye in the electrolyte. For mirrors
one of the TC is generally replaced by a multilayer structure
comprising a metallic reflector overcoated with a transparent
conductor. Some of the materials used for the reflective layer
comprise silver, aluminum, rhodium, ruthenium, their alloysand the
transparent conductors are usually indium tin oxide and aluminum
zinc oxide. Chromium and titanium layers may be used to promote
adhesion of the metallic layers to the substrate.
[0052] Type B device (FIG. 6) principally comprises of a multilayer
system deposited on a single substrate 4a. The layers deposited on
this substrate are usually all inorganic. Such a device is built by
taking a substrate and depositing a TC layer (4b) with a
composition described in Type A device followed by an inorganic
ion-conductor layer and then followed sequentially by an EC layer
(4c) CE layer (4e) and another TC layer (4f). Sometimes these
devices are laminated with another piece of glass to provide
mechanical and chemical protection to the underlying layers. The
laminating polymers are typically the same which are used for glass
lamination and discussed above. The electrolyte layer (4d)
comprises of oxides and nitrides of several materials such as
lithium, phosphorous, aluminum, silicon and others. The electrolyte
layer may comprise of more than one layer with different
compositions to improve the compatibility with the EC and the CE
layers.
[0053] The busbars in the devices may be metallic clips, conductive
frits and metal tapes with conductive adhesives which span at least
one side of the substrate (sometimes two or all sides) for each of
the TC layer in a device. Conductive frits usually have metal
oxides and silver metal, the spring clips are made of steel nickel
and copper alloys, and the tapes are usually copper which may be
tin plated to prevent corrosion and be able to easily attach the
soldered connectors to them. The tapes have conductive adhesive on
one side which usually comprises of an organic pressure sensitive
adhesive with conductive particles dispersed in it. In addition to
these components in the Type A devices there is a perimeter
adhesive (not shown) to protect the interior of the device,
particularly the EC layer, CE layer and the electrolyte. These
organic materials are usually thermosetting polymers.
[0054] The materials of construction of smart windows are briefly
described above to help understand the complexity of the materials
variety present in the smart windows, which have to be considered
for an effective recycling process.
[0055] The foregoing description of the invention has been
presented for purposes of illustration and description and is not
intended to be exhaustive or to limit the invention to the precise
form disclosed, and obviously, many modifications and variations
are possible considering the above teaching. The embodiments were
chosen and described to best explain the principles of the
invention and its practical application to thereby enable others
skilled in the art to best utilize the invention in various
embodiments and with various modifications as are suited to the use
contemplated. It is intended that the scope of the invention be
defined by the claims appended hereto.
* * * * *